The invention relates to check valves in general, and more particularly to improvements in check valves of the type wherein a tubular housing confines a reciprocable valving element which is biased against an internal seat of the housing by a spring or the like so that the valving element normally seals the fluid-admitting inlet of the housing from the fluid-discharging outlet. Still more particularly, the invention relates to improvements in check valves of the type wherein the housing further contains a core with guide members for the valving element.
In presently known check valves of the above outlined character, the core has a single annular section which is connected with the housing and has a set of prong-like guide members which are adjacent the internal surface of the housing and serve to confine the valving element to reciprocatory movements between its sealing and open positions. When in sealing position, the valving element prevents the flow of a fluid through the housing in either direction, and the valving element invariably prevents the flow of a fluid in a direction from the outlet toward the inlet of the housing. Thus, if the pressure at the inlet of the housing is less than at the outlet, the spring automatically shifts the valving element into engagement with the seat so that no fluid can enter, by way of the check valve, a conduit which serves to supply fluid to the inlet of the housing.
Champion U.S. Pat. No. 2,800,142 discloses a check valve wherein the core has a number of axially parallel prongs which serve to guide the valving elements and each of which has a free end remote from the annular section of the core A drawback of the patented valve is that the core occupies too much space in the housing because it must be provided with a large number of sturdy and bulky guide members. The guide members must be sturdy and bulky because only one end of each such guide member is integral with an annular part of the core. Moreover, the guide members offer a rather pronounced resistance to the flow of a fluid through the housing of the patented check valve in open position of the valving element. If the guide members are made of a thermoplastic material, they are likely to undergo undesirable deformation in response to heating by the conveyed fluid or by the housing of the check valve; this can affect the accuracy of guidance and can lead to jamming of the valving element. Thermally induced expansion of the guide members also promotes jamming of the valving element. On the other hand, the clearances between the guide members and the adjacent portions of the valving element cannot be too pronounced because radial stray movements of the valving element can result in the generation of noise. Guide members of thermoplastic material exhibit the additional drawback that they are prone to deformation immediately after they leave an extruder or another making machine, and such prong-like guide members are likely to become entangled with the guide members of neighboring cores during storage and/or during transport to the machines which are used to insert the cores into the corresponding housings.
A check valve with a modified core or cage member for the reciprocable valving element is disclosed in Clark et al. U.S. Pat. No. 2,918,083. The prong-like guide members of the core have inwardly bent tips which are anchored in the housing. The other end of each guide member is integral with a disc-shaped bottom wall which serves as a retainer for the valve spring.
German Utility Model No. 66 10 152 (owned by the assignee of the present application) discloses a check valve wherein only the shank of the reciprocable valving element is guided, namely by a sleeve-like bearing which is installed in the housing adjacent the outlet.
German Utility Model No. 16 97 174 of Sandmann discloses a check valve wherein the housing is provided with integral internal ribs which serve to guide the reciprocable valving element.